The long term goal of the proposed study is to develop guidelines for the safe use of genetic testing for hereditary colon cancer, specifying the indications and contraindications, and the preparatory and follow-up counseling that will minimize harm and maximize the cancer-prevention benefits of testing. The proposed study addresses three aims. Aim 1 is to identify the demographic, psychological, and medical factors that distinguish those who accept from those who decline genetic testing for colon cancer. Aim 2 is to evaluate the immediate and later-developing effects of testing on psychological well-being and screening behavior. There is a particular focus on the risks on inconclusive genetic tests. The commercial availability of the tests for hereditary colon cancer and the shortage of genetic counselors increase the likelihood that patients will be inadequately prepared for testing and be prone to misconstrue inconclusive results as true negative, leading to false reassurance about their cancer risk. False reassurance may lead to undesirable decreases in cancer screening and prevention efforts. Aim 3 is to identify similarities and differences in willingness to consider genetic testing for colon cancer between Caucasian and African-American persons. Aims 1 and 2 will be accomplished in a 3-year, repeated measures longitudinal study involving 300 adults at risk for colon cancer that will examine the effects of predictive testing for colon cancer on psychological well-being and colon cancer screening-behavior. Colon cancer-specific psychological distress will be examined separately from general psychological distress (depression, anxiety) and both will be measured at baseline and at 1, 6, 12, 18, and 24 months after disclosure of the genetic test results. Based on the genetic test results, recommendations for colonoscopy will be made, and adherence with these recommendations will be assessed at the same time points. Subjects will complete two pre-testing sessions of genetic and psycho-educational counseling. Data will be collected via interviews, surveys, and investigator and informant ratings. Aim 3 will be accomplished through representative sampling of African-Americans in the gene testing study and a mail survey of 200 African-American adults at risk for colon cancer, for comparison to a previously surveyed sample of Caucasian adults.